You are right about the shift and keying speed (850 Hz at 75 baud). What
appears to be a doubling of the keying speed is actually Mark-Space
reversals, still sent at 75 baud.

The signal is not bulk encrypted but individual messages seem to be.

The reversals are sent before the beginning of a message and again
after the end of it. I also observed periods of unmodulated
carrier sent between periods of reversals, probably while the operator
changed tapes or loaded another message into the computer or crypto device.

If I listened carefully, it seemed that the beginning of some messages
contained a rhythmic pattern which lasted a few seconds. I looked for a
frame pattern, out to 226.8 msec (the limit of my software) but found
none, so this introductory pattern must be longer than that. Also I could
find no frame pattern within the bits of a message (more evidence of
encryption), out to 226 msec.

The freqs you mentioned aren't listed in my 2003 Klingenfuss list of
utility stations, so I guess it is a relatively new station.

Have you checked the Worldwide Utility News (WUN) website?? (Sorry I
don't have their URL.) Some of their monitors might be able to ID the
station. (It's not in an exclusive Amateur band, so it's not a problem
for me HI)

73,
.... Martin VE3OAT

IARU Region 2 Monitoring System Coordinator
www.storm.ca/~iarumsr2
("the intruder watch folks")


gudmundur ) writes:
There are four very strong signals here on the east coast of U.S.A., I here
them best after dusk.

3.084mhz 3.102mhz 3.126mhz and 3.132mhz

Here is what I know,

1000hz center frequency
850hz shift
75baud / 13.3ms so it would appear


The signal stops erratically on both space and mark tones. Also, at
times the baud rate seems like it becomes very fast, perhaps double.

I hear this same exact 'signature' signal in many places, on many bands,
and can't seem to decode it with normal 5 level baudot programs. However,
the signal doesn't seem to be ascii either.

Anyone want to give a listen, and tell me what I need. Are they encrypted,
or do I just need a different rtty-to-text convertor?

TNX KD3SH